Disclaimer: I don't own the Avengers.
Second disclaimer: these ficlets might not have the same polish as the rest of my writing, because they were all written in little snatches on my phone during slow times at work. They're all very fluffy, though, and I hope you enjoy them anyway!
The onesies appear one day when Steve's just coming home from a day of SHIELD training. Tony gets them, because he's a giant dork.
Baby Peter is Pooh Bear, and he looks so freaking adorable in his soft little red and yellow bear suit that Steve can barely handle it when he comes in and finds his two best boys curled up warm and cosy, playing pop the cheeks.
Peter's shrieking in excitement, sitting on Tony's stomach and clapping his chubby hands against Tony's puffed-out cheeks to make them pop, again and again. Steve watches them quietly for a few minutes, his heart feeling so full and warm that it could burst.
Then Tony glances up and sees him, and his eyes light up. 'Daddy's home!' he says to Peter, and swings him up in the air and comes over to Steve.
That's when Steve sees that Tony's in a onesie too, and oh god, is he trying to kill his husband with the cuteness? Tony's onesie is orange and black, tiger striped, and Tony's bouncing up and down with Peter in his arms, saying 'Onesie day! I'm Tigger!'
'Tigger!' Peter yells.
'No, you're Pooh,' Tony tells him. 'Pooh Bear, red and gold, because they're the best colours, aren't they, pudding?' Tony always calls Peter 'pudding', because he's so fat and round.
Steve laughs and opens his arms and pulls them both in, kissing Peter's downy head and the smiling corner of Tony's mouth. 'Love you,' he murmurs, and Tony melts into him, onesie and all. Peter wraps his little arms around Steve's neck for a hug, and Steve holds them both, breathing in the quiet smell of his little family.
'There's a onesie for you too,' Tony says after a bit, nestling into Steve's neck. He's trying to hide a grin, and Steve narrows his eyes at him and flips the hood over his face.
Tony giggles. 'Hey, stop it, you brute,' he says, wrinkling his nose and pushing the hood out of his eyes. 'I had to get it made to fit, because you're so freakishly big.' He traces gentle little circles on Steve's chest with his fingers. 'You'll love it.'
Peter is Pooh Bear, and Tony is Tigger. So naturally, Steve… is Piglet.
He loves it.
'You're adorable,' Steve tells Tony later, when they're all three snuggling together on the couch, Peter sleepy and happy and sucking on his bottle, splayed out across Steve's chest.
Tony grins where he's tucked against Steve's neck, stroking Peter's silky hair with gentle fingers. 'Says the giant man in a Piglet onesie.'
Steve kisses his forehead, nuzzling into Tony's warmth. 'I love the onesie,' he says softly. And Tony nestles against him, because they both know he really means I love you.
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